[pottereric]

The other factor to consider here is that not all specialists are focused on a technology. Some specialists focus on a process or a business domain. If a startup is working on financial software, finding someone that has a deep knowledge of finance software might be incredibly valuable. This could be very true if your software needs to meet regulatory requirements like Sarbanes Oxley.

[zaidf]

I assumed the context here was developers. For other kind of specialists, they can be INSANELY valuable from the get-go. In fact, one of the first hires I'd recommend anyone doing enterprise startup is hiring a domain specialist. These people are relatively inexpensive and add tremendous value in giving product feedback between early iterations. They can also talk to early customers with more credibility and thus help adoption of certain features that the customer may other not see much value in.

[pottereric]

Actually, I was talking about developers. In my experience working on projects that needed FDA part 11 compliance, it can be incredibly helpful to have developers that know how to write software that meets to compliance rules from process, validation, and auditability standpoints. I presume the same is true for SOX or HIPPA.